Device and process for synchronous control of bicycle derailleurs

ABSTRACT

Device for management of two derailleurs for cycles. The device comprises actuating levers connected to two derailleur gears by transmission cables (C 1 , C 2 ). It is characterized in that it comprises a cam (26, 81, 82) which is driven in rotation with respect to a second element (42, 64) by the action of actuating levers and which acts on an element of a fixed part (12, 60) of the device. The reaction of the fixed part induces a movement of a part (20, 71, 72) of the device carrying at least one of the elements and on which the transmission cables are integral. The movement occurs simultaneously with the rotation of the first element (26, 80), so that traction is exerted at the same time in the same direction on the transmission cables (C 1 . C 2 ), one of which is caused to move. The device is particularly useful in the cycle industry.

FIELD OF THE INVENTION

The present invention relates to bicycle derailleurs and moreparticularly to devices for controlling these derailleurs.

BACKGROUND OF THE INVENTION Bicycles or cycles in general, are thesedays most often provided with a rear derailleur or free wheel derailleurand a forward or pedal derailleur.

The forward derailleur guides and positions the chain on two or threechain rings. The rear derailleur performs a similar job on six or eightpinions. There result substantial lateral displacements of the chain andthis increases the risk of placing the chain in torsion with thedrawbacks that result therefrom (poor performance, chain disengagement,wear on parts, etc.). This same increase in the number of relativeratios gives rise to a greater complexity in the choice of these latterand errors are frequent (gear changing involving a large increase ineffort, error in the direction of manipulation of the shift levers,calculation necessary before changing speed, a need to control visuallythe position of the chain to know the action to take).

Devices have already been proposed tending to solve these differentproblems but none has solved all of them.

For example, FR-A-2,530,573 has for its object a device for controllingtwo derailleurs, comprising two actuating members each connected to twoderailleurs by a transmission member, the device comprising amanipulating member of one of the actuating members connected to theother actuating member by a lost motion connection.

This arrangement permits, by a single control member, controllingsimultaneously the two derailleurs and the lost motion connectionprovided in the transmission permits offsetting the control of the pedalderailleur relative to the control of the free wheel derailleur.

Such a device solves the problem of misalignment of the chain but givesrise to a jolt in pedaling due to the amplification of the abruptness ofchanging the gear by a change of pinion in the same direction.

U.S. Pat. No. 4,412,828 describes a simultaneous control device for afront derailleur with two chain rings and a rear derailleur with fivepinions by means of a system of cams and cam followers. This device isadapted to actuate step by step the rear derailleur to the centralpinion and change of gear while remaining on this central pinion, thenactuating step by step for the remaining pinions. This known device usesin practice half the pinions for each respective level. It isdifficultly adaptable to modern derailleurs with three levels and morethan five pinions. Moreover, the simultaneous control is continuous,which gives rise to a long path for the control member and bulkiness ofthe assembly.

U.S. Pat. No. 4,412,828 describes a simultaneous control device forderailleurs, for example with two levels and five pinions, ensuring tenratios by this combination. This system, which requires practicallyalternate changes of level with the simultaneous passages from one orseveral pinions, ensures a transmission ratio varying in a continuousmanner. This device, which would be very complicated for a large numberof gear ratios, does not concern itself with the angle of the chain.

Moreover, all the known devices are controlled by a shift lever or ahandle which can occupy as many positions as there are usable speeds,such that the cyclist must pay attention to the effective position ofthe shift lever before actuating it in one direction or the other.Moreover, as indicated in connection with U.S. Pat. No. 4,412,828, sucha device is bulky because of the long path of the control member.

SUMMARY OF THE INVENTION

The present invention has particularly for its object to overcome thisdrawback while proposing a mounting which renders highly visible for theuser all relative displacements of the derailleur, which displacementscan be controlled by impulse.

To this end, the invention relates to a device for controlling twoderailleurs for bicycles comprising actuating means connected to the twoderailleurs by transmission means, as well as a first member adapted tofollow a cycle of simultaneous displacement of the two derailleurs,acting in combination with a second member adapted to fix the initialpositions of each of the cycles, characterized in that said first memberis a cam driven in rotation relative to a second member under the actionof actuating means, and acting relative to an element of a fixed portionof the device, whose reaction gives rise to the displacement of amovable part of the device carrying at least one of said members, and onwhich are integral the transmission means, the displacement taking placesimultaneously with the rotation of the first member, so as to ensuresimultaneous traction in the same direction on said transmission means,while effecting a displacement of one of these means.

According to a characteristic of the invention, the movable part carrieson the one hand the first member or cam and on the other hand the secondmember constituted by a cylinder, with which cylinder are integral thetransmission means and whose rotation effected by the actuating meansgives rise, by means of a demultiplier, to the rotation of the cam.

According to an embodiment of the invention, the cam is articulated inrotation about a fixed axle integral with the movable part, by means ofa circular hole from the center of which are provided a plurality ofholes receiving the indexing means of radius E and mutually orthogonal,whose centers lie on a circle of radius R and at a variable distancefrom the edge of the cam respectively equal to X+r+R, X+r+R+Y, X+r+R+2Y,etc., to constitute a pre-selected program.

The invention also relates to an improved process for simultaneouscontrol of two derailleurs.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be illustrated without any limitation by thedescription which follows, given in respect to the accompanyingdrawings, in which:

FIG. 1 is a fragmentary view of a bicycle showing

sideways the control device according to the invention;

FIG. 2 is a cross-sectional view on line II--II of FIG. 1 according to afirst embodiment of the invention;

FIG. 3 is a cross-sectional view on line III--III of FIG. 2;

FIG. 4 is a cross-sectional view on line IV--IV of FIG. 2;

FIGS. 5A-5K show schematically the successive relative positions of thecontrol elements of a device according to the invention during passagefrom the least to the greatest gear ratio;

FIGS. 6A-6K show schematically the successive positions of the chain inthe sequences corresponding to FIGS. 5A-5K;

FIG. 7 shows by way of example a control device of the succession of thesequences 5A-5K;

FIG. 8 is a transverse cross-sectional view of a control deviceaccording to a second embodiment of the invention;

FIG. 9 is a cross-sectional view on the line IX--IX of FIG. 8; and

FIG. 10 is a developed view of a cylinder of the device according toFIGS. 8 and 9 in which are provided the grooves in the shape of a ramp.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a part of a cycle frame C provided with a handlebar G inrelation to which are disposed in a very schematic fashion (see FIGS. 6Ato 6K) three chain rings P1, P2, P3 and a free wheel which comprisesseven pinions R1, R2, R3, R4, R5, R6, R7.

Two derailleur mechanisms (not shown) which can be of conventionaldesign and construction are provided to make the chain CH pass from onepinion R to the other and from one chain ring P to the other.

These two derailleurs are actuated respectively by transmission meansconstituted by cables C₁ and C₂. FIG. 1 shows only the beginning ofthese cables.

The control device is constituted by actuating means, in this case twolevers L1 and L2, mounted by any appropriate means on either side of thehandlebar G. These levers serve when moved to exert traction on controlcables CC1 (respectively CC2) which are disposed in sleeves of ordinarytype G1 (respectively G2) which guide the cables to the control device10 for the derailleurs. These levers are thus comprised in known mannerof a device for securement to the handlebar or to the brake lever, of afixed abutment sleeve, of a device for blocking the cable pin and forexerting traction on this pin which is articulated about an axis andwhich will not be described here.

The other end of each cable CC1 and CC2 extends to the interior of thecontrol device for the derailleurs.

This derailleur control device is fixed to the frame by any appropriatemeans, two collars 11A and 11B in this example, preferably on thediagonal tube of the frame C, in a location adapted not to interferewith the movement of the forward wheel and of the mud guard.

The control device 10 comprises a guidance table 12 forming a rightparallelepiped on which will be fixed removably a rotation axle 13 whichsupports an abutment 14 free to rotate about this axle and if desiredone or two devices for the adjustment of displacement (not shown in thedrawings), adapted to demultiply the initial displacements of the cablesC₁ and C₂ to adapt them to the required displacement for each derailleurwhich is associated with them (this displacement being adapted to varyfrom one model of derailleur to another). These adjustment devices canbe staged pulleys or lever arms or any other appropriate means.

A housing 20 can slide on the table 12 by means of slideways 21A and21B, when the axle 13 is removed. A window 22 is provided in the base ofthe housing 20 to permit mounting the axle 13 and the longitudinaldisplacement of the housing 20 relative to the table 12.

The housing 20 comprises a removable cover 23 which is fixed to it byany appropriate means. The housing 20 comprises moreover a cylindricalaxle 24 on which are mounted a toothed wheel 25 and a cam 26. The cam 26bears against the abutment 14 under the action of the tension of cablesC₁ and C₂. The cam 26 is pierced by four holes 26A, 26B, 26C, 26D spaced90° about a circle whose center is located on the axle 24.

As a function of the rotation of the cam 26 about the axle 24, thesefour holes receive alternatively balls 27A and 27B of a diameter greaterthan the diameter of the holes 26A to 26D. These balls 27A and 27B areguided in linear displacement by calibrated holes 23A and 23B providedin the cover 23. These holes are pressed against the cam 26 by means ofa spring 28 whose pressure is adjusted by the gripping more or lessstrongly of a nut 29 on the axle 24.

The assembly of members 24, 26, 27, 28 and 29, with the guide holes 23Aand 23B, thus permits an indexing in rotation of the cam 26 each 90° .

The cam 26 has a particular contour which responds to the followingcriteria:

during a rotation of 90° , from the position corresponding to thesmallest radius toward the following position, this radius increases bya value Y;

during a similar rotation from this new position, the same is true;

likewise a third time;

during the following similar rotation, this radius diminishes abruptlyby 3Y to return to the initial contour after one complete turn.

This special contour of the cam 26 thus defined is one of the essentialcharacteristics of the invention.

A cover 24A is screwed on the axle 24 to ensure protection from dirt inthe interior of housing 20, while permitting easy access to theadjustment of the difficulty of indexing the cam 26.

A toothed wheel 25 secured to the cam 26 drives in rotation the toothedwheel 32 (and vice versa) itself fixed to the toothed wheel 33. Theselatter two are mounted on an axle of rotation 31 secured to the housing20. The toothed wheel 33 drives in rotation the toothed wheel 41 (andvice versa) which is itself fixed in rotation with a cylinder 42. Thewheel 41 and the cylinder 42 are fixed to an axle 40 adapted to turn inthe housing 20. The cylinder 42 supports on opposite sides of itsperiphery (FIG. 4) the cables C₁ and C₂ by any conventional means.

The cables C₁ and C₂ are then guided toward the adjustment membersdescribed above (if they exist) then actuate in the usual manner thedeformations of the front and rear derailleurs of the cycle.

The toothed wheel 41 and the cylinder 42 are simultaneously controlledin rotation by a control device 5 constituted by a lever 52 articulatedon the axle 40, driven over an angular interval under the action intraction of cable CC1 or CC2 by means of a member 53 on which is fixedthe end of cable CC1 and which is resiliently urged by a resilientmember 51 in the form of a pin.

The traction of cable CC1 effects, through a pawl 54 of the member 53, arotation of the toothed wheel 41 and of the cylinder 42 in the directionopposite that of the traction of cable CC2.

The traction of CC1 (or CC2) therefore causes a rotation of the toothedwheel 41 and of the cylinder 42 comprised between 0° and at leastone-third of the total rotation possible for this assembly (41, 42),this in a manner to pass beyond at least one position of the cam 26.After traction of the cable CC1 (or CC2), the resilient member 51returns the lever L1 (or L2) to its initial position by means of thecable CC1 (or CC2).

After the return of the actuated lever L1 or L2, the pawl 54 permits therotation of the assembly 41-42 in either direction without the tractiveaction of cable CC1 or cable CC2 provided that the cylinder 42 has notreached one of its end positions.

The cylinder 42 is adapted to wind up the cables C₁ and C₂ about aradius which corresponds to the following equation:

wherein D is the demultiplication caused by the succession of thetoothed wheels 25, 32, 33 and 41:

    D=Nb teeth 41.Nb teeth 32/(Nb teeth 33.Nb teeth 25);

Y is the length about the cam 26 as defined above;

R is the radius of cam 42 in question, thus:

    R=2.Y.D:Pi.

It will thus been seen that the assembly of the toothed wheels preventsa winding of the cables C₁ and C₂ about a too small radius, which wouldbe a source of problems of precision and wear, given the rigidity ofthese cables.

The operation of the control device which has been described is asfollows:

Considering first that the chain occupies the position shown in FIG. 6A,which corresponds to the minimum demultiplication ratio possible, themembers 14, 26, 42, C₁ and C₂ occupy the positions schematically shownin FIG. 5A, which is to say the maximum elongation.

An elemental force AE1, exerted on the toothed wheel 41 and the cam 42by the lever L1 by means of the cable CC1 connected to the controlmember such as described above, causes the cylinder 42 to turn by 90°/D, which drives the rotation of the cam 26 through 90° . These newpositions then correspond to FIG. 5B. The cable C₁ is thus subjected tothe following movements:

unwinding about the cam 42 over a length Y, which effects thedisplacement of the assembly relative to the fixed axle 13 toward theassociated derailleur, namely the rear derailleur.

return of the axle 42 by a length Y because of the rotation of the cam26 (this is again a displacement toward the associated derailleur).

Thus the cable C₁ displaces toward the derailleur which is associatedwith it by a length 2Y.

In the same time the cable C₂ is subjected to the followingdisplacements:

winding about 42 by a length Y (away from the derailleur);

approach of the axle 42 by a length Y (toward the derailleur).

Thus the cable C₂ does not move.

As a function of the adjustment members, optionally present, thisresults in:

deformation of the rear derailleur which causes passage of the chainfrom the pinion R1 to the pinion R2;

no variation in position of the forward derailleur.

This new position of the chain is represented in FIG. 6B.

From this position, the reverse action (-AE1) returns to the precedingposition.

From these positions shown in FIGS. 5B and 6B, a new elemental actionAE1 causes the new positions of the cylinder 42 and the cam 26 shown inFIG. 5C. As in the stage described above, C₁ displaces by a length 2Dtoward its associated derailleur and C₂ remains stationary. As a result,the chain occupies the position shown in FIG. 6C. And a new action AE1results in the positions of the members as seen in FIG. 5D and in aposition of the chain in FIG. 6D.

Thereafter, and this is a major feature of the invention, a newelemental action AE1 produces a result very different from that of thepreceding actions:

the cam 42 and the cam 26 will come to occupy positions shown in FIG.5E. These new positions cause the following movements:

For the cable C₁ :

unwinding about 42 by a length Y (toward the derailleur);

spacing of the axle 42 by a length 3Y (away from the derailleur);

Balance: spacing of the derailleur by a length 2Y, which effects risingof a pinion (from R4 toward R3);

For the cable C₂ :

unwinding about 42 by a length Y (opposite the derailleur);

spacing of the axle 42 by a length 3Y (away from the derailleur);

Balance: spacing of the derailleur by a length 4Y, which is effective,when using if desired adjustment members, to deform the forwardderailleur to effect the passage from chain ring P1 to chain ring P2.

The new position of the chain is shown in FIG. 6E.

From there, the sequence 5E, 5F, 5G, 5H, 5I is equivalent to thesequence 5A, 5B, 5C, 5D, 5E and leads to the positions of the chainsseen in the respective FIGS. 6E, 6F, 6G, 6H, 6I.

And finally, the sequence 5I, 5J, 5K is equivalent to the sequence 5A,5B, 5C which gives the positions of the chains shown in 6I, 6J, 6K.

The end position of the chain corresponds to the greatest ratio and isthus achieved.

Thanks to the control device described above, it is possible in eachposition of the chain to exert a control AE1 or -AE1 which leads to thefollowing or preceding position of the chain, or to exert a control oflarger amplitude, which permits modifying more rapidly the position ofthe chain while skipping over several stages at a time.

There are thus available a total of eleven different suitably graduatedratios. The passage from the longest ratio toward the shortest (or viceversa) is effectuated by an elemental action on the left or right lever.The optimum alignment of the chain is always preserved. The path of thecontrol member permits passing through several ratios at a time ifdesired. The indexation permits systematically placing the derailleurssuch that the chain will engage perfectly in the pinion and the selectedchain ring.

Of course, numerous other variations combining a linear displacementwith an unrolling of the cable will lead similarly to the desired endand to numerous other arrangements than that proposed can be envisaged.Likewise, the combination of toothed wheels can be replaced by any otheranalogous system or by the use of a more flexible cable to connect thecylinder 42 to the adjustment device. This device for adjustment of thelength permits the mounting of no matter what derailleur on the cyclebut is not necessary. The cams 26 and 42 can be designed to effectsuitable displacements of the cables which correspond to the changes ofposition of the chain. Finally, the control device may be any, providedthat it responds to the stated criteria. The return of the levers L1 andL2 to the initial position after actuation is not indispensable but ishighly preferable from an ergonomic point of view.

According to a modification shown in FIGS. 8, 9 and 10, the controldevice differs essentially from the preceding in that it is constitutedby a fixed table 60 secured to the cycle either on the frame C by meansof two collars as in the preceding example, or on the handlebar G of thecycle, the control then taking place directly by turning the handlebareither in one direction or the other, which gives rise to the successiveoperations avoiding the necessity of providing another actuating device.

In this table 60 is provided a longitudinal groove 61 constituting aguide means in translation for the two carriages 71 and 72.

Two bearings 62 and 63 permit the mounting of a threaded rod 64, ofspecial pitch, which is fixed relative to the table 60.

A cylinder 80 can be screwed by means of a threaded central hole on therod 64. The periphery of the cylinder 80 is indented by two grooves inthe form of two ramp-shaped grooves 81 and 82 whose development is shownin FIG. 10.

The groove 81 receives at its lower portion the lug 71A secured to thecarriage 71, while the groove 82 receives similarly the lug 72A of thecarriage 72.

The carriage 71 (or 72) is provided with a conventional pin blocking thecable of the derailleur 71B (or 72B) and can thus exert a traction onthe cable C₁ (or C₂) which controls the rear or forward derailleur. Forconvenience, a pulley 90 returns the cable C₂ so that it leaves from thesame side of the device as the cable C₁.

Adjustment members for the necessary lengths of each derailleur can beinstalled on the device using the corresponding mounting described forthe preceding system, it being noted however that the pulley 90 can beadapted to fulfill this function as to the cable C₂. The adjustmentmembers have not been shown in these figures.

The operation of this device will now be described with reference toFIGS. 6A to 6K, 8, 9 and 10.

In initial position, the chain occupies on the pinions the positionshown in FIG. 6A. The device is actuated by an elemental action AE1which causes cylinder 80 to turn by 90° about the threaded rod 64. Thisrotation has the following effects:

For the cable C₁ :

displacement of the lug 71A relative to the ramped cylinder 80 under theaction of the groove 81 which is not in the plane perpendicular to theaxle 64 and braking of the lug 71A in the recess

83 of the groove 81 to constitute an indexation in rotation of thecylinder 80 each 90° .

this displacement has a length L toward the right in FIG. 9.

simultaneously, the cylinder 80 is gripped on the threaded rod 64 and,given the pitch and orientation of these threads, this effects adisplacement of said cam for a length L toward the right in FIG. 9.

In conclusion, the cable C₁ displaces over a length 2L toward the right.

For the cable C₂ :

the groove 82 being oriented symmetrically to the groove 81,

the carriage 72 has a movement relative to the cylinder 80 of a length Ltoward the left in

FIG. 9. Simultaneously, the cylinder 80 displaces by L toward the rightof FIG. 9.

In conclusion, the cable C₂ does not move in the course of this firstelemental action.

These displacements are of a nature to effect deformations of the rearand front derailleurs of the cycle which result in positioning the chainas shown in FIG. 6B.

A new elemental action AE1 produces the same effects and leads to thechain position shown in FIG. 6C; and the next time to produce theposition of FIG. 6D.

The fourth elemental action AE1 leads to different results from those ofthe preceding actions:

For the cable C₁ :

the groove 81 undergoes a movement relative to the lug 71A of anamplitude 3L relative to the cam 80 toward the left in FIG. 9. Thismovement is compensated by the gripping of the cam 80 on the axle 64which drives said cam by L toward the right of FIG. 9.

In conclusion, the cable C₁ moves by a length 2L toward the left in FIG.9.

For the cable C₂ :

the groove 82 effects a relative movement of the lug 72A of an amplitude3L toward the right in FIG. 9 and the gripping of the cam 80 on the axle64 adds L to this displacement.

In conclusion, the carriage 72 displaces by a length 4L toward the rightof FIG. 9.

These simultaneous displacements of the cables C₁ and C₂ are of a natureto deform the front and rear derailleurs of the cycle to lead to theposition of the chain shown in FIG. 6E.

Further elemental actions AE1 then effect the progress of the same cycleof displacement of the two derailleurs starting from this new beginningposition.

It will therefore be seen that, in this arrangement, the threaded rod 64constitutes the member which fixes the initial positions of eachcommencement of the cycle of movement of the derailleurs, while thegrooves 81 and 82 disposed on the cam 80 constitute the members which gothrough the cycle of displacement of the rear derailleur (for the groove81) and of the front derailleur (for the groove 82).

This new mounting is thus another example of the application of thegeneral principle defined initially.

Definitions of symbols:

X=Number of descents of the rear derailleur before rising.

LR=Length of the cable to obtain each change of a pinion to the rear.

LCR =Length of cable displaced under the action of the member whichdescribes the cycle of operation of the rear derailleur.

LIR=Length of cable displaced under the action of the member whichdefines the initial conditions of each cycle of the rear derailleur.

The notation is similar for the forward derailleur by replacing R withV.

Operation of the rear derailleur:

During a pinion descent, we have: LR=LCR+LIR and thus X times.

During rising of the pinion, we have: -LR=-X.LCR+LIR

From which follows:

    LCR=2·LR/(X+1)

    LIR=LR·(X-1)/(X+1)

Operation of the forward derailleur:

During no change, we have: LCV-LIV=0 and thus X times.

During change of chain ring, we have: LV=X.LCV+LIV

From which follows:

    LCV=LV/(X+1)

    LIV=LV/(X+1)

The device which has been described can comprise various modifications.The control housing can be mounted on the handlebar, and can beardirectly on the control members, so as to permit the user to keep holdof the handlebar and obtain a simplified assembly, easier to mount, andless bulky.

In this way the housing 20 with its linear displacement can be replacedby a beam with pendulous movement. The position of the axis of pivotingof this beam can be chosen so as to limit the bearing force on the cam,so as to facilitate the rotation of this latter.

Instead of direct action on the cables C₁ and C₂ by the member 20,sliding or oscillating, it can be provided to fix on this member 20 theabutments or hangers of each of the sleeves of these cables C₁ and C₂.The bearing of the member 20 on the cam 26 is thus effected by thetension of the cables themselves. A shock absorber device can beprovided to diminish this bearing force, particularly during passages ofthe cam from the smallest to the largest ratio during a rotation of 90°. The displacement of the sleeves is equivalent to a displacement of thecables in the illustrated example.

I claim:
 1. Control device for two derailleurs for bicycles comprisingactuating means connected to the two derailleurs by transmission means(C₁, C₂), as well as a first member (26, 80) adapted to move through acycle of displacement of the two derailleurs simultaneously, acting incombination with a second member (42, 64) adapted to fix the initialpositions of each of these cycles,wherein said first member is a cam(26, 81, 82) driven in rotation relative to the second member (42, 64)under the action of actuating means, and acting relative to an elementof a fixed portion (12, 60) of the device, whose reaction gives rise tomovement of a part (20, 71, 72) of the device carrying at least one ofsaid members, and to which are fixedly secured the transmission means(C₁, C₂), the displacement taking place simultaneously with the rotationof the first member (26, 80), so as to ensure a traction which issimultaneous and in the same direction on said transmission means (C₁,C₂), while giving rise to a displacement of one of these means relativeto the other in one direction or the other according to a predeterminedprogram.
 2. Device according to claim 1,wherein said movable part (20)is slidably mounted.
 3. Device according to claim 2,wherein the movablepart (20) of the device moves on a fixed part secured to an element ofthe cycle by means of longitudinal slideways (21A, 21B).
 4. Deviceaccording to claim 2,wherein the movable part is constituted by twocarriages (71, 72) adapted to slide simultaneously in a longitudinalgroove (61) in a fixed table (60) in one direction or the other underthe conjugated action of two peripheral ramps (81, 82) which are notorthogonal relative to the axis of a cylinder (80) on which they areprovided, said cylinder (80) being adapted to translate on a fixedthreaded rod (64), during a rotative control exerted on it, the ramps(81, 82) mating respectively with lugs (71A and 72A) of the carriages(71, 72) on which are fixed the transmission means (C₁, C₂).
 5. Deviceaccording to claim 1,wherein said movable part (20) is oscillablymounted.
 6. Device according to claim 1, wherein the cam (26) isarticulated in rotation about a fixed axle (24) fixed to the movablepart (20), by means of a circular hole from the center of which extend aplurality of holes (26A, B, C, D) housing indexation means of radius r,and orthogonal to each other, whose centers lie on a circle of radius Rand at a variable distance from the edge of the cam (26) respectivelyequal to X+r+R, X+r+R+Y, X+r+R+2Y, and so on, to constitute apredetermined program, wherein X is the distance between the edge of thecam and the edge of a first of said plurality of holes, X+Y is thedistance between the edge of the cam and the edge of the second of saidplurality of holes, X+2Y is the distance between the edge of the cam andthe edge of a third of said plurality of holes, and so on.
 7. Deviceaccording to claim 6,wherein the indexation means are constituted by atleast one ball (27A and 27B) of a diameter greater than the holes (26A,B, C, D) on which they bear and which are guided in linear displacementin graduated recesses (23A, 23B) provided in a wall forming a cover ofthe movable part (20) of the device, said balls (27A, 27B) bearingresiliently against the cam (26) by a resilient member (28).
 8. Deviceaccording to claim 7,wherein the resilient member (28) is adjusted inpressure by gripping more or less strongly by a nut (29) screwed on afree end of the axle (24).
 9. Device according to claim 1 wherein themovable part (20) carries on the one hand the first member or cam (26)and on the other hand the second member (42) constituted by a cylinder,to which cylinder are fixedly secured the transmission means (C₁, C₂)whereby the rotation effected by the actuation means (L1, L2) givesrise, by means of a demultiplier (25, 32, 33, 41), to the rotation ofthe cam (26).
 10. Device according to claim 9,wherein the demultiplier(25, 32, 33, 41) is a gear train.
 11. Device according to claim 1,wherein the transmission means are cables having sleeves with abutmentsor hangers which are fixed to said movable part (20).
 12. Synchronizedcontrol process for two derailleurs for bicycles of which one ensuresthe passage of the chain from one pedal chain ring to another pedalchain ring and the other ensures the passage of the chain from onepinion to another of the free wheel, comprising: when the chain tends toassume an inclination greater than a given limit, passing the chain fromone chain ring to an immediately following chain ring and passing thechain from one pinion to an immediately adjacent pinion, said passagestaking place by variation in the same direction of the number of teethof the chain ring and of the pinion.